Resize Image for Email Newsletter Banners
Email newsletter banners need to be exactly sized for email client compatibility. Most email templates use a 600px wide container. ImageGates resizes your header images and banners to fit perfectly in Mailchimp, ConvertKit, Klaviyo, and any email platform.
Email banner dimensions for Gmail, Outlook and Apple Mail
Email clients cap the readable width at roughly 600 px, and Outlook desktop does not scale images down responsively. A banner must therefore be built at 600 px display width and supplied at 2× for retina screens.
Exact specifications:
- Display width: 600 px
- Upload size (retina): 1200×400 px, displayed at 600×200
- Total email weight: under 100 KB of images ideally, 500 KB maximum
- Formats: JPG or PNG — WebP is unsupported in Outlook desktop
- Gmail clipping threshold: 102 KB of HTML
What causes a rejected or degraded result:
- Building one large image-only email; images are blocked by default in many clients and the reader sees nothing.
- Using WebP, which Outlook desktop cannot display.
- Omitting the width and height attributes, which makes Outlook render the file at its full pixel size.
Preparation order that avoids rework:
- Design at 1200 px wide and set the HTML width to 600.
- Compress to under 150 KB.
- Always add descriptive alt text so a blocked image still communicates the message.
How to use this tool
- Upload banner image — Select your newsletter header design or promotional banner.
- Resize to 600px wide — ImageGates resizes to the standard 600px email container width.
- Use in email platform — Download and add to your Mailchimp, ConvertKit, or other email template.
Guide
Email newsletter images must balance quality with deliverability. Large images increase email size, which can trigger spam filters and slow loading times.
Email image best practices: - Standard width: 600px (1200px for retina) - Header/banner: 600 x 150-250px - Full-width content image: 600px wide - Product thumbnails: 200-300px wide - File size: Under 200KB per image - Total email weight: Under 1MB
Email client compatibility: - Outlook: Displays most JPG/PNG, blocks SVG - Gmail: Good support, auto-proxies images - Apple Mail: Excellent rendering - Mobile: Auto-scales to screen width
Email platform recommendations: - Mailchimp: 600px container, recommends 1200px for retina - ConvertKit: 600px container - Klaviyo: 600px or custom widths - Constant Contact: 600px standard
Frequently asked questions
What width should email images be?
The standard email container is 600px wide. Use exactly 600px for full-width images. Some modern templates support 640px or even 700px, but 600px is the safest choice.
Why are my email images blurry?
Many email clients display on high-DPI (retina) screens. Upload images at 2x size (1200px) and set the width to 600px in HTML for sharp display on all screens.
Open Image Resizer